/*
 * base64-arraybuffer
 * https://github.com/niklasvh/base64-arraybuffer
 *
 * Copyright (c) 2012 Niklas von Hertzen
 * Licensed under the MIT license.
 */

interface Base64 {
    chars: string
    lookup: null | Uint8Array
    encode(arraybuffer: ArrayBuffer): string
    decode(base64: string): ArrayBuffer
}

var Base64: Base64 = {
    chars: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
    lookup: null,
    encode: function(arraybuffer: ArrayBuffer) {
        var chars = this.chars;
        var bytes = new Uint8Array(arraybuffer),
            i, len = bytes.length, base64 = "";

        for (i = 0; i < len; i += 3) {
            base64 += chars[bytes[i] >> 2];
            base64 += chars[((bytes[i] & 3) << 4) | (bytes[i + 1] >> 4)];
            base64 += chars[((bytes[i + 1] & 15) << 2) | (bytes[i + 2] >> 6)];
            base64 += chars[bytes[i + 2] & 63];
        }

        if ((len % 3) === 2) {
            base64 = base64.substring(0, base64.length - 1) + "=";
        } else if (len % 3 === 1) {
            base64 = base64.substring(0, base64.length - 2) + "==";
        }

        return base64;
    },
    decode: function(base64: string) {
        var chars = this.chars;
        var lookup = this.lookup
        if (!lookup) {
            lookup = this.lookup = new Uint8Array(256);
            for (var i = 0; i < chars.length; i++) {
                lookup[chars.charCodeAt(i)] = i;
            }
        }
        var bufferLength = base64.length * 0.75,
            len = base64.length, p = 0,
            encoded1, encoded2, encoded3, encoded4;

        if (base64[base64.length - 1] === "=") {
            bufferLength--;
            if (base64[base64.length - 2] === "=") {
                bufferLength--;
            }
        }

        var arraybuffer = new ArrayBuffer(bufferLength),
            bytes = new Uint8Array(arraybuffer);

        for (i = 0; i < len; i += 4) {
            encoded1 = lookup[base64.charCodeAt(i)];
            encoded2 = lookup[base64.charCodeAt(i + 1)];
            encoded3 = lookup[base64.charCodeAt(i + 2)];
            encoded4 = lookup[base64.charCodeAt(i + 3)];

            bytes[p++] = (encoded1 << 2) | (encoded2 >> 4);
            bytes[p++] = ((encoded2 & 15) << 4) | (encoded3 >> 2);
            bytes[p++] = ((encoded3 & 3) << 6) | (encoded4 & 63);
        }

        return arraybuffer;
    }
}

export default Base64